1. Field of the Invention
The present invention relates to a method and an apparatus of obtaining directivity in an optical waveguide, and a recording medium for storing the directivity. It particularly relates to a method of obtaining directivity in an optical waveguide which is used in an optical selector switch and the like.
2. Description of Related Art
A multistage optical selector switch according to a multipoint-to-multipoint system has studied and developed accompanying an expansion of long-distance multiplex communication technology using an optical cable.
Specifically, there have existed an optical switch of optical-fiber-driving type that changes optical paths by directly driving a fiber with a magnetized cover by means of electromagnet, an optical switch of micro mirror type that changes passing optical paths by changing a reflection angle of light using an MEMS mirror, an optical switch of waveguide type that switches the light on or off by, after separating light into its two spectral components that are different in a phase, performing a phase inversion on one spectral component of the light and interfering with it to original light, and a multistage optical selector switch using an optical sheet bus. The multistage optical selector according to a multipoint-to-multipoint system has been configured based on these technologies to switch a communication signal.
Such an optical switch, however, is expensive and has a large cabinet so that it is unsuitable for built-in to any general consumer appliances.
Japanese Patent Application Publication No. H10-123350 has disclosed a system in which any functions of a product are modularized so that the functions can be easily added or exchanged on an optical sheet bus.